Separation and recovery from mixed industrial wastes, comprises process based on flotation, with further stages of comminution, pulping, screening and digestion to yield metals, minerals, gas and compost

摘要

Waste is comminuted and subjected to water flotation, separating sinks and floats. In addition, a suspended fraction is drawn off, including floating material. Any water-soluble and/or suspended components of the suspended fraction are dispersed or dissolved in a pulper, from which a floats fraction is withdrawn. A second suspension fraction is withdrawn from the pulper over a screen. A second sinks fraction is withdrawn from the pulper. Preferred Features: Matting, floating materials from flotation, are drawn off from an upper region of the flotation tank. They are comminuted and sent to the pulper with the first suspension fraction. Comminution is dry, no water being added, and a shredder or crusher being employed. To largely remove or suspend the water soluble and/or suspended components in the pulper, one or more washing stages are effected. Each washing stage is carried out by drawing off each suspension in the pulper over the sieve, making up with additional water and renewed, brief mechanical energy input. Pretreatment of waste includes mechanical isolation of solids by breaking up pressed components, opening baling straps and removing any transport constraints, before comminution. Materials capable of causing blockage are removed before comminution. Following addition of water to the waste for flotation or pulping, temperature is raised to 70 deg C-90 deg C for sanitation. Floats and/or the first and/or the second sinks are washed after separation. From floats, one or more plastic fractions are separated, by density-based separation or by selective dissolution. Plastic fractions are prepared for re-use or incineration by shredding, drying and/or granulation. The second suspension fraction is fed to an aerobic reactor.